WinSCP 5.10 with OneDrive support has been released.
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Works rather fine with CarotDAV, but the developer version 5.10 stops with error "Could not sent request body: an existing connection was closed by remote host" (translated from German) after 47 - 130 MB (tried it several times).
So I think it is a WinSCP limitation / bug.
Please send me a copy too, I have the same error.
This issue has been added to the tracker:
I'll send you a development version for testing shortly.
One remark: files more then 100 MB are breaks off (not uploaded until the end). But, it is not a fault of WinSCP. Apparently, it's a limitation of the OneDrive webdav access itself.
Please, send me an email, or register on the forum.
I'm facing the very same issue.
Can I get a developer version too?